1. Field of the Invention
The present invention relates to an ink-jet printing apparatus and a printing method to be employed therein for performing printing on a common paper or OHP sheet (transparent sheet having an ink receptacle layer) under a reference printing condition, or a production method of an ink-jet printed article obtained through printing. More specifically, the invention relates to a printer and a printing system which is capable of printing on a common paper and a cloth.
2. Description of the Related Art
Associating with spreading of information processing apparatus, such as copy machines, wordprocessors, computers and so forth and communication apparatus, an ink-jet type printing apparatus are spread as one of apparatus for outputting images processed by the systems set forth above. This type of printing apparatus employs an ink-jet head for forming ink dot on a printing medium to perform digital printing. Many of such apparatus has a printing mode for performing printing employing a transparent sheet with an ink receptacle layer, i.e. so-called OHP sheet as the printing medium. In this mode, in comparison with printing on the common paper, with respect to a black ink, for example, twice greater amount is ejected toward the OHP sheet.
On the other hand, a dedicated ink-jet textile printing apparatus have been put into practical use. In such textile printing apparatus, it becomes possible to produce high precision and high density printing clothes employing dedicated ink-jet recording heads specifically adapted for the textile printing. However, this kind of ink-jet textile printing apparatus are all adapted for industrial application and not for the personal use to permit the user for easily printing. For instance, Japanese Patent Application Laying-open No. 55277/1986 discloses an ink-jet textile printing apparatus dedicated for industrial textile printing. In the disclosed apparatus, a cloth for ink-jet printing containing substantially non-exhaustive compound to the dye as an elemental material of the cloth in a content of 0.1 to 50 Wt % is employed for preventing bleeding of ink in the cloth.
In contrast to this, in the printing apparatus for performing printing on the common paper, there has been proposed apparatus which can perform printing on the clothes Reference is made to commonly owned Japanese Patent Application Laying-open No. 53492/1987. In the above-identified commonly owned publication, there are disclosed a step of forming a recording liquid (ink) receptacle layer having viscosity higher than or equal to 1 Pa s at 25 xc2x0 C. in the cloth, overlaying the cloth with such printing liquid receptacle layer with a paper and instantly setting the overlaid cloth and paper in the ink-jet printer, and performing printing, and a step of iron fixing the printed cloth and thereafter removing the printing liquid receptacle layer by using neutral detergent to obtain the printed product. This proposal also employs dedicated printing medium with improved ink receptacle layer to permit image of a predetermined density with achieving enhanced resolution and prevention of blurring and bleeding.
Also, Japanese Patent Application Laying-open No. 61183/1990 discloses an invention for improvement of the cloth per se with paying attention to a difference between the ordinary printing medium, such as the common paper, to be employed in normal printing and cloth, as printing medium. In order to increase surface density in the cloth in performing ink-jet printing, and thus for the purpose of increasing residual ratio of coloring agent of ink in the cloth, a coating layer is formed by coating a non-exhaustive high polymer compound on the whole cloth or the surface of the cloth to be printed, another coating layer is formed on the surface opposite to that to be printed by coating a high polymer compound for preventing ink from flowing out through this surface and whereby increasing residual rate of the ink on the cloth.
In the conventional industrial textile printing as set forth above, the ink-jet head and the apparatus per se can be dedicatedly set adapting to the characteristics of the cloth to be employed. Also, dedicated ink adapted to the ink receptacle layer in the cloth can be prepared (for instance, employing a reactive dye ink). Furthermore, in the industrially performing textile printing, it is not necessary to perform ink-jet printing on the plain paper. Therefore, the apparatus can be used under freely set conditions in consideration of only textile printing.
While the common characteristic construction of the conventional textile printing apparatus is that the diffusion of ink in the cloth is suppressed by the ink receptacle layer for achieving desired density, it can merely achieve improvement of the image quality in the extent that the density of the image to be formed by the ink is maintained by concentrating the ink at the predetermined position. However, such construction is to suppress diffusion of ink and whereby concentrate the ink at predetermined position to maintain the desired density, but cannot achieve further higher density.
On the other hand, the printing apparatus normally available in the market and set primarily for printing on the common paper and so forth employing the ink-jet technology, can perform precise and fine printing on the basis of a color image data transmitted from a host system, and thus is useful for a compact and inexpensive color ink-jet printing apparatus. The ink to be employed in such printing apparatus is normally prepared employing dye or pigment, e.g. direct dye, adapted for printing on the common paper In the OHP printing mode as selective mode in the printing apparatus available in the market, which is set primarily for the paper, such as plain paper, twice greater amount of ink than the printing on the plain paper in the predetermined area is ejected for emphasizing black. Accordingly, when printing on the cloth is performed by means of the conventional field printing apparatus set for the common paper or so forth as the printing medium as disclosed in Japanese Patent Application Laying-open No. 53492/1987, the printed image quality should have been excellent in the light of the technical level at the time of application, it cannot achieve satisfactorily high density and high quality of printed image.
It is an object of the present invention to provide an ink-jet printing apparatus, a printing system which can print on both of cloth and paper, with high density and high printed image quality superior to the conventional level of image quality in a field printer device set in view of printing on paper, such as a common paper as a printing medium, an ink to be employed in the system set forth above, and a method for producing a product to be produced with employing the system set forth above.
Another object of the present invention is to provide an ink-jet printing apparatus, with which a user can easily print precise and fine image on a cloth utilizing characteristics of existing general purpose ink-jet printing apparatus and with solving the problems of difference of ink absorbing condition due to difference of fibrous tissue and surface configuration, and difference of coloring characteristics between the paper and the cloth.
A further object of the present invention is to solve the problem in the prior art and to provide a printing system which enables to optimally utilize characteristics of the ink-jet printing in printing on the cloth and the paper by providing printing condition effective for adaption to difference of ink absorbing condition and coloring characteristics of the cloth due to difference of fibrous tissue and surface configuration and without requiring improvement of the ink receptacle layer in the cloth, for the field printing apparatus set typically for paper, such as the common paper and so forth.
A still further object of the present invention is to provide a printing system which enables to optimally utilize characteristics of the ink-jet printing in printing on the cloth and the paper by providing an appropriate printing condition for printing on the cloth with a color ink other than black ink.
A yet further object of the present invention is to provide a printing system which is capable of excellent printing on both of the cloth and the paper by providing an appropriate condition depending upon the kind of the cloth in improving the printed image quality for the cloth utilizing a reference for the field printing apparatus which is set with taking the paper, such as the common paper as reference for the printing medium.
It is observed a phenomenon specific to the cloth newly found during study for improvement of the printing quality for the cloth utilizing the reference for the plain paper of the field printing apparatus that near the allowable limit of ink absorption, abrupt deformation is caused in the cloth to cause significant cockling in the extend not being conventionally expected from the behavior of the paper. In such case, while the improvement of the density of the image can be achieved, since the cloth per se is fixed in the cockling condition, the quality of the final product can be degraded. Accordingly, it is another object of solve this new problem.
An improvement of the image density adapted to cloth can be achieved with utilizing mode for performing printing on the common paper under the reference printing condition by providing an ink-jet printing apparatus employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head while the ink-jet head and the printing medium are relatively moved, comprising preferential mode for performing printing under conditions as taking a plain paper as reference of the printing medium, cloth printing mode for performing printing on a cloth with setting a condition, in which at least one of the conditions in the preferential mode is set for higher image quality, and the preferential mode being set preferentially to the cloth printing mode, and the cloth printing mode is performed in place of the preferential mode when the cloth printing mode is set.
A still further object of the invention is to provide an ink-jet printing system present which can perform excellent printing both on the cloth and the paper by preferentially providing appropriate printing condition depending upon the kind of the cloth upon improving printed image quality for the cloth utilizing a reference for the field printing apparatus which is set with taking the paper, such as the common paper as reference for the printing medium.
In order to improve operability for the operator without causing complexity and facilitate setting of reasonable printing mode utilizing the reference for the common paper of the printer, conditions for printing can be set by a host computer which generates an image signal by differentiating at least one of the conditions in the cloth printing preferential printing mode from a printing condition in a mode for performing printing on other printing medium, and one or more cloth printing preferential modes for performing printing on the cloth and switching means for selecting one or more cloth printing preferential mode can be set on the apparatus performing printing operation according to the image signal to be printed.
The effective and concrete content of the present invention is an ink-jet printing system which can eject a plurality of colors of inks and the ink ejection amount for the printing medium is increased for at least one of the colors among a plurality of inks, and in the ink-jet printing system which can eject a plurality of colors of inks, among inks to be ejected in the ink-jet printing system capable of ejecting a plurality of colors of inks, the ejection amount of the ink for black color printing is set to be greater than or equal to the ink ejection amount for other colors.
It should be noted that, in the present invention, the cloth to be employed as the printing medium includes all of woven fabrics, non-woven fabrics and other clothes irrespective of the elemental material, weaving type, thickness. There are a large number of kinds of fibers forming the clothes from natural fibers to synthetic fibers, which have wide variety of ink absorbing characteristics. Therefore, even for increasing the ejecting amount of the ink to the cloth, the amount to be ejected cannot be determined in straightforward manner. Also, in application of the ink-jet printing system for the textile printing, there are wide variety of images (patterns) to be printed, for which high density is not always desirable. Furthermore, when the image (pattern) is not only a single color but also a multi-color, it is quite possible to require different density per color. Therefore, even when printing is performed on the cloth by the ink-jet system, it is substantially not possible to provide one printing mode adapted to the cloth in general sense as the printing medium to perform printing for clothes of all conditions. For instance, when a multi-color image is to be printed and when the densities are differentiated per colors, it may be possible to express such variation of the density by tone production method by density of each element, such as dither method and so forth. However, in such case, greater number of tones may results in lowering of resolution and requires longer period in image signal processing. For example, when the image to be printed has high image density, it can be insufficient to have the dedicated mode.
As set forth above, in order to adapt the ink-jet system to variety of clothes, it can be insufficient to have one kind of printing mode for clothes separately from the printing mode for papers. Therefore, it is desirable to provide capability of setting more kinds of cloth printing modes. It is further desirable to provide capability of automatically or manually switching one or more cloth printing modes. In addition, in certain content, it may be possible to have a printing mode common to the conventional system. Therefore, it is a further object of the present invention to provide an ink-jet printing system which can easily improve the level of the system without making the system bulky and causing increasing of the cost.
For realizing printing in ink-jet system, digital form image is handled for forming the image by dots. Accordingly, in the ink-jet printing system, a host computer is provided for performing digital conversion or signal processing of the image signal and feeding an ejection signal to an ink-jet head. In such case, it becomes possible to perform switching of setting of the cloth printing mode set forth above on the computer simultaneously with feeding of the image signal. In particular, there has been progressed a GUI (Graphic User Interface) environment and bidirectional communication is becoming possible. Such system is useful.
Alternatively, switching of setting of the cloth printing modes as set forth above, can be performed at an ejection control portion of the ink-jet head. Therefor, is possible to perform switching at the side of the printing apparatus. This manner is advantageous in comparison with switching performed by the host computer, since switching can be instantly performed with verifying the actual printing image.
In the case where different density is expressed per color, it is effective to permit appropriate setting of the ink ejection amount per each color. Generally, when a multi-color image is expressed, the image can be expressed employing four kinds of colors, i.e. black, cyan, magenta and yellow. From this, setting of the ejection amount of respective inks by providing setting of the increased ejection amount for at least one color. Particularly, when the density of the black is higher than that of other colors, sharpness can be clearly seen on the printed image. Therefore, it is effective to permit black to be ejected in greater amount than that of other colors.
In a first aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head while the ink-jet head and the printing medium are relatively moved, comprising:
setting means for setting one of a cloth printing mode for performing printing on a cloth and another printing mode for performing printing on another printing medium; and
printing control means for performing printing operation for the printing medium corresponding to the printing mode, the printing mode being set by the setting means.
In a second aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head while the ink-jet head and the printing medium are relatively moved, comprising:
print control means performing printing by repeating operation of reciprocating the ink-jet head on the printing medium and operation for feeding the printing medium;
the print control means performing ejection ink during forward and reverse travel of the ink-jet head and completing printing for each region defined by dividing a printing region of the cloth through a plurality times of reciprocating operation when the cloth is employed as the printing medium.
In a third aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink-jet head and performing printing corresponding to a set printing mode by ejecting an ink to a printing medium from the ink-jet head while the ink-jet head and the printing medium are relatively moved, comprising:
preferential mode for performing printing under conditions as taking a common paper as reference of the printing medium;
cloth printing mode for performing printing on a cloth with setting a condition, in which at least one of the conditions in the preferential mode is set for higher image quality; and
means for setting the preferential mode preferentially to the cloth printing mode, and for setting the cloth printing mode in place of the preferential mode when the cloth printing mode is selected.
In a fourth aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head while the ink-jet head and the printing medium are relatively moved, comprising:
reference cloth printing mode for performing printing on a cloth with taking a color ink printing condition for printing by ejecting different colors of inks, and a black ink printing condition for printing by ejecting black ink different from the different colors of inks as preferential condition; and
selected cloth printing mode for performing printing under a condition, in which at least one of the color ink printing condition and the black ink printing condition is modified depending upon the kind of the cloth; and
means for setting the selected cloth printed mode in place of the reference cloth printing mode when the selected cloth printing mode is selected.
In a fifth aspect of the present invention, there is provided an ink-jet printing system employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head while the ink-jet head and the printing medium are relatively moved, comprising:
one or more cloth printing preferential modes for performing printing on a cloth; and
switching means for selecting the one or more cloth printing preferential modes;
wherein conditions of a printing made for performing printing on other printing medium can be set by in differentiating at least one of the conditions in the cloth printing preferential printing mode a host computer which generates an image signal.
In a sixth aspect of the present invention, there is provided an ink-jet printing system comprising:
a plurality of ink tanks storing a plurality of inks, the plurality of inks being exchangeable depending upon the cloth to be used, and respective of the plurality of inks being the ink defined in claim 19.
In a seventh aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink head mechanism which can eject a plurality of colors of inks, and performing printing by ejecting inks from the ink-jet head mechanism to a printing medium while the ink-jet head mechanism and the printing medium are moved relatively to each other, comprising:
preferential printing mode being a preferential mode and taking a maximum ink amount to be provided per unit area of a common paper for color ink different from black ink as reference printing condition;
reference cloth printing mode being a mode for printing on a cloth and setting a maximum ink amount at double of the reference printing condition for the color inks and at three times of the reference printing condition for the black ink;
selected cloth printing mode for performing printing under a condition which is set by modifying at least one of the maximum ink amount to be provided in the unit area of the color ink and the black ink in the reference cloth printing mode, depending upon a kind of cloth; and
means for setting the selected cloth printing mode in place of the reference cloth printing mode.
In an eighth aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head according to a set printing mode while the ink-jet head and the printing medium are relatively moved, comprising:
preferential printing mode for performing printing under a reference printing condition on an OHP sheet as preferential mode;
cloth printing mode for performing printing on the cloth under conditions in which at least one of conditions in the reference printing mode in the preferential printing mode is modified to a condition for higher image quality; and
means for setting the preferential printing mode preferentially to the cloth printing mode and for setting the cloth printing mode in plane of the preferential printing mode when the cloth printing mode is selected.
In a ninth aspect of the present invention, there is provided an ink-jet printing apparatus employing an ink-jet head and performing printing by ejecting an ink to a printing medium from the ink-jet head according to a set printing mode while the ink-jet head and the printing medium are relatively moved, comprising:
preferential printing mode for performing printing under a reference printing condition on a plain sheet as preferential mode;
cloth printing mode for performing printing on the cloth treated for stiffening to have clark stiffness greater than or equal to 10 and smaller than or equal to 400 and containing a polarized dye fixing agent under conditions in which at least one of conditions in the reference printing mode in the preferential printing mode is modified to a condition for higher image quality with increased ink ejection amount; and
means for setting the preferential printing mode preferentially to the cloth printing mode and for setting the cloth printing mode in place of the preferential printing mode when the cloth printing mode is selected.
In a tenth aspect of the present invention, there is provided an ink-jet printing system comprising:
a host computer connected to the ink-jet printing apparatus as defined in claim 31 and generating an image signal to be printed, on which host computer, the ink ejection amount per unit area for the black ink and the color ink other than black ink can be modified to have the upper limit at less than or equal to four times of the reference printing condition in the preferential printing mode.
Next, the printing method adapted to the present invention is characterized by thinning of the image data to be printed according to the predetermined image data pattern, performing ejection of the ink with reciprocally moving the ink-jet head in the primary scanning direction according to the thinned image data, and at every reciprocal movement of the ink-jet head, forming the image by feeding the printing medium in a distance less than or equal to the length of the ejection orifice string.
In viewpoint of printing on the cloth, the present invention is directed to the objective image for printing, which image is primarily a multi-color image rather than the monochrome image. When such image is to be printed, a divided printing as discussed later is frequently employed. Namely, upon printing the color image, various characteristics, such as color development ability, toning ability, uniformity and so forth have to be excellently achieved in comparison with character printing. Particularly, concerning uniformity, the following problem has been known conventionally. Namely, in the ink-jet head, in which a plurality of ejection orifices are arranged, small tolerance in the configuration of respective individual ejection orifices caused during production process, may cause fluctuation in ejection amount and ejecting direction of the ink ejected from respective ejection orifices. This results in fluctuation of density of the printed image and thus causes degradation of the image quality. The concrete example will be discussed with reference to FIGS. 21 and 22. In FIG. 21A, a reference numeral 91 denotes an ink-jet head, in which a plurality of ejection orifices are arranged. It should be noted that, for the purpose of illustration, the ink-jet head is assumed to be constituted with eight ejection orifices 92. The reference numeral 93 denotes an ink droplet ejected from the ejection orifices 92. It is ideal that the ink droplet is uniform in ejection amount and ejecting direction and is not deflected. When ejection can be performed in this manner, uniform size of dots can be formed, and whereby uniform image without fluctuation of the density through overall image can be obtained (see FIG. 21C). However, in practice, each ejection orifice fluctuates in ejection characteristics to cause fluctuation in the ink droplet size and ejecting direction as ejected through such ejection orifices as shown in FIG. 22A when printing is performed in the same manner to the above. Then, dots are formed as illustrated in FIG. 22B. In the example of FIG. 22B, it becomes not possible to completely fill the printing area with dots formed by the ink droplet ejected along the primary scanning direction (left and right direction in the drawing). As a result, on the overall surface of the printing medium, blank portions appear cyclically. Also, it forms the portion, in which the dots overlaps excessively. Further, as can be seen at the center of FIG. 22B, it may leave blank (white) band. The image formed by an aggregate of the dots formed in the manner set forth above may have the density distribution with respect to the arrangement direction of the ejection orifices as illustrated in FIG. 22C, which should appear for the human eye as density fluctuation.
As a measure for such density fluctuation, the following method has been proposed, The method will be discussed with reference to FIGS. 23A to 23C and 24A to 24C. In the method, as shown in FIG. 23A, for completing printing in a region shown in FIGS. 21A to 22C, the ink-jet head 91 is scanned three times. However, in the half of the region shown in FIGS. 21A to 22C, i.e. in a region where four pixels are arranged, printing is completed by scanning twice. In this case, eight ejection orifices in the ink-jet head is divided into upper four ejection orifices and lower four ejection orifices and are differentiated the scanning regions for respective groups of ejection orifices. The dots formed by ejection of ink through ejection orifices at the first scanning cycle are thinned into approximately according to a predetermined data array (hereinafter referred to xe2x80x9cprint maskxe2x80x9d). In the second scanning cycle, the dots are formed for the remaining half of the image data to complete printing for respective regions. Such method of printing is hereinafter referred to as xe2x80x9cdivided printing methodxe2x80x9d. By employing such divided printing method, even when the ink-jet head which otherwise causes fluctuation in formation of dots as illustrated in FIGS. 22A to 22C, is employed, the fluctuation can be absorbed since the dots in the scanning direction are formed with mutually different two ejection orifices. As a result, the printed image becomes as illustrated in FIG. 23B. As can be seen from FIG. 23B, the black band or white band become not so perceptible. Accordingly, the density fluctuation on the printed image can also be absorbed as illustrated in FIG. 23C, in comparison with the case illustrated in FIG. 22C.
Upon performing printing in the manner set forth above, the image data is divided in complementary manner according to a predetermined array for the first and second scanning cycles. This typical image data array (thinning pattern) is to exclude every other dot data in vertical and lateral directions in lattice fashion. Therefore, in a unit printing region (here an array of vertical four pixels), printing is completed by printing in lattice fashion in the first scanning cycle and by printing in reversed lattice fashion in the second scanning cycle. FIGS. 24A, 24B and 24C illustrate the process how the printing is progressed with employing the lattice and reversed lattice patterns when the ink-jet head having eight ejection orifices similar to those of FIGS. 21A to 23C. At first in the first scanning cycle, printing of the lattice pattern is performed employing lower four ejection orifices to form the hatched dots (FIG. 24A). Then, in the second scanning cycles, paper is fed for four pixels (half length of the ejection orifice array) and printing of the reversed lattice pattern (non-hatched dots) is performed (FIG. 24B). At the third scanning cycle, paper is further fed for four pixels (half length of the ejection orifice array) and printing of the lattice pattern (hatched dots) is performed (FIG. 24C). As set forth above, by repeating paper feeding for four pixels sequentially and by alternately performing lattice pattern printing and reversed lattice pattern printing, printing for an array of four pixels is completed al every scanning. As set forth, by completing printing for one printing region by ejection through mutually different ejection orifices, it becomes possible to obtain high quality image with lesser density fluctuation.
Also, since the ink density to be simultaneously ejected on the cloth becomes low, penetration of ink in the depth direction becomes lesser. Therefore, it can be expected that greater amount of coloring material of tile ink, such as dye and so forth, can be maintained on the surface of the printing medium and thus to achieve higher printing color density. From this point of view, the printing method set forth above, which is applied to the present invention, may be quite effective for cloth printing.
While the foregoing discussion has been given for the construction where printing is completed by scanning the same printing region twice, the divided printing method may be more effective at greater number of dividing. For instance, by reducing the number of pixels to he printed in one scanning cycle to be half and setting paper feeding magnitude in each scanning cycle to be the magnitude corresponding to two pixels, printing for dots arranged in the scanning direction is completed by four mutually different ejection orifices. Therefore, the density fluctuation can be further reduced to provide better quality of image with increased printing color density.
Next, further advanced construction in the case where the divided printing system is applied for the textile printing, will be discussed. Namely, when reciprocative printing is performed, due to deflection of ejecting direction of each individual ejection orifice to differentiate the dot forming positions at forward printing and at reverse printing. Also, in color printing, the order of ejection of respective color inks is differentiated between the forward printing and reverse printing. The difference of printing conditions between the forward printing and the reverse printing should significantly affect for printed image quality. For example, when different colors of inks are ejected in overlaying manner to the same position or a thin line is drown, difference of shifting direction of the dot forming position in forward printing and reverse printing may cause disturbance of the image. Also, in the case where the different colors of inks are overlaid at the same position, reversal of ejecting order may cause variation of the color taste of the color generated by mixing the colors. For this, it is difficult to accurately control the dot forming position of the ejected inks in the forward and reverse printing and to appropriately control penetration of the ink. Therefore, the normal mode printing is typically performed as one-way printing instead of reciprocative printing.
In the study made by the inventors with respect to behavior in performing printing on the cloth by means of the ink-jet printing system, it has been found that the foregoing problem is rarely caused. Namely, irrespective of the order of ejection, the ink reaching the cloth is absorbed with uniformly spreading in the cloth. By this, the diameter of the dot to be formed becomes relatively large and in view of the feeling of the cloth print, not so strict dot forming position precision is required. Therefore, reciprocative printing system is effective in the case where the cloth is employed as the printing medium.
Namely, in comparison with conventional printing on the paper, lesser constraints in application of the divided printing method for printing on the cloth are applicable. Therefore, the divided printing method can be further advanced. For example, when the cloth printing mode is selected, an appropriate print mask may be selected depending upon the kind of the cloth to be printed. Also, overlaying printing for the same portion of the cloth can be done freely. Also, the image printing density can be determined arbitrarily. By this, higher quality and printing on the cloth and widening of applications can be achieved. For example, by determining the adequate print mask, the ink-jet head can be reciprocally scanned according to the selected printing mask with setting the ink ejection amount freely, at a rate of 100%, 200%, 300%, 400%, 500% and so forth
In the setting of the ink ejection amount, as a condition for solving the problem of significant cockling of the cloth in the extent cannot be expected from the behavior of conventional paper printing, due to abrupt deformation near the allowable limit of ink reception, it can be employed that the maximum ink ejection amount per unit area in printing on the cloth is limited to be greater than the maximum ink ejection amount with taking maximum ink ejection amount upon printing on the common paper as reference, but less than or equal to three times (optimally double) of the maximum ink ejection amount in common paper printing, with respect to the color inks, and to be greater than the maximum ink ejection amount with taking maximum ink ejection amount upon printing on the common paper as reference, but less than or equal to four times (optimally three times) of the maximum ink ejection amount in common paper printing, with respect to the black ink. A reference cloth printing mode preferably has above-described condition to make ejected ink amount per unit area of the cloth to be maximum.
Also, the preferred condition of the ink to be employed in the present invention, is that the ink is a water base ink containing surface active agent, the content of the surface active agent is less than critical micell concentration with respect to the ink and is greater than the critical micell concentration with respect to the water when water is added to the surface active agent. The inks are used in such a manner that a plurality of ink tanks respective containing a plurality of kinds of inks for ink-jet printing system are exchangeable depending upon the cloth to be employed. It should be appreciated that as application of the present invention, it is possible to perform printing either by directly printing on the cloth or by printing on another transfer medium and subsequently transferring the printed image on the transfer medium to the cloth utilizing the feature of the present invention.
As the ink to be used in the ink-jet system, inks capable of forming excellent image on the common paper available in the market and having high penetration speed with little bleeding at the boundary have been developed recently. In contrast, when printing is performed with conventionally available ink, penetration speed for the common paper normally available in the market is low to cause unnecessary color mixture at the boundary between the simultaneously printing dots. Therefore, bleeding is caused at the boundary of the colors to cause degradation of the printed image quality. Particularly, in a graphic image, such as graph, a part of table, drawn picture and so forth, it is frequently require to print overall area of a portion of the image with a single color ink. In such case, employing the ink having high penetration speed, in addition to setting of the printing condition according to the present invention, degradation of the image quality can be successfully prevented.
Also, certain kinds of common paper may have fluctuation of the ink penetrating conditions on the paper surface to cause degradation of uniformity or local tinting can be caused in the portion printed with the single cover (this portion will be hereinafter referred to as xe2x80x9csolid print portionxe2x80x9d). It is considered that degradation of the solid print portion as set forth above is caused due to non-uniformity of the surface of the common paper. Due to non-uniformity of the surface of the common paper, the ink droplet ejected penetrates selectively through a portion having low water repellency caused by gap between fibers, sizing agent and so forth. This results in formation of irregular configuration of dot, such as star shaped configuration, instead of the circular dot. Conventionally, such problem cannot be solved without employing a paper with a special coating. However, most of such coated papers are expensive and distributed through a limited route. Therefore, employment of such coated paper is not typical for the field users.
However, it is effective measure for the problem set forth above to improve penetration ability and penetration speed of the ink into the common paper by adding the surface active agent in the preferred condition according to the present invention to the ink. Addition of the surface active agent may causes significant increasing of viscosity of the ink near the ejection orifice due to evaporation under low temperature environment when the excess amount of the surface active agent is added. This can cause difficulty of maintaining the ejection performance by normal recovering process Also, lowering of surface tension to the limit and elevating of the viscosity may cause degradation of convergence of the ink droplet to cause spreading of the ink as ejected to cause primary droplet and subsequent fine droplets (satellite). By generation of satellite, degradation of the image quality, such as degradation of the character quality or of the straightness of rules. Furthermore, due to increasing of viscosity of the ink, refiling after ejection takes relatively long period to affect for ejection frequency.
In order to satisfactorily solve the problem set forth above, it is necessary to adjust the amount of the surface active agent in view of critical micell concentration versus ink and versus water within an appropriate range. The commonly owned Japanese Patent Application No. 164845/1993 discloses that higher concentration of the surface active agent is desired in view point of promotion of penetration of ink into the printing medium, and that, in view point of prevention of bleeding and maintaining uniformity of solid print, it is practically required that the amount of the surface active agent is to be greater than critical micell concentration in the water, and in view of improvement of the ejection characteristics, improvement of unit dot quality and facilitating of recovery process, the amount of the surface active agent is to be less than the critical micell concentration versus the ink.
As set forth above, for the ink-jet printing system capable of excellent printing for a plurality of kinds of printing media including the cloth, which the present invention seeks for, the ink having relatively high penetration characteristics by adding the surface active agent as set forth above is effective. In particular, such ink is quite effective when it is applied for cloth printing mode. Since it is possible that the ink ejection amount for the cloth is greater than that for the paper, the normal ink is not satisfactory in the relative ink absorption speed. Therefore, in such case, when different colors of inks are ejected at relatively high speed, mixture of color with the adjacent and different color ink droplet is caused before complete absorption of the ink in the cloth. Such mixture of the colors is perceptive as bleeding of the boundary of the color. In order to prevent this, there can be considered such approaches to increase number of multi pass to progress printing with drying inks, and to provide a waiting period of carriage per one cycle of scanning to wait for absorption of the ink. However, either method tries to promote drying by taking a time, it requires longer period for outputting the image than that required in printing with other printing medium. In view of this, by employing the penetration drying ink containing the surface active agent, absorption and drying of the ink can be done instantly. Therefore, it becomes unnecessary to spend a time for drying the ink and high printing color density can be attained. By providing penetration ability of the ink by addition of the surface active agent, ink absorption ability into the fiber forming the cloth can be improved to make it possible to attain uniform dying of the fiber near the surface of the cloth. Also, it becomes possible to prevent the ink from excessively penetrating in the cloth in the depth direction. Therefore, the ink added the surface active agent is applicable as the ink suitable for cloth printing mode.
In addition to this, it is effective to employ a reactive dye which has been frequently used in the conventional textile printing technology, as coloring agent to be contained in the ink, for applying the cloth printing mode for greater number of kinds of clothes. In the case of ink employing the reactive dye, while direct fixing ability is low, it becomes possible to obtain hue with clear and high durability on the cloth by reaction of xe2x80x94OH group in the fiber and the dye by applying alkali treatment for the cloth.
Also, as the ink, any appropriate inks can be employed as long as the necessary coloring material is contained, the ink containing not only the dye but also pigment can be employed.
When a plurality of kinds of inks can be utilized, it is the preferred construction of the ink-jet printing system according to the present invention to store a plurality of applicable inks in ink tanks and to use them with exchanging depending upon the cloth to be printed. The inks of respective colors are not required to be the same kind of inks in four colors and two or more kinds of inks can be used in combination to mixedly set in the ink-jet system. For instance, it is possible to use ink with normal penetration ability to be used for paper for black, and to use highly penetration drying type inks added the surface active agent for other colors, i.e. cyan, magenta and yellow. With this combination, even in the even ejection amount for all colors, the black ink may be maintained near the surface of the cloth in the greater amount than other colors to make the density of black higher than other colors.
On the other hand, various inks listed above is applicable not only for printing on the cloth but also on other printing media. Accordingly, in the ink-jet printing system according to the present invention, it is possible to appropriately select ink per se in conjunction with selection of the printing mode depending upon the printing medium.
Next, application of the present invention is a producing method of ink-jet printed article characterized that it is possible to perform printing either by directly printing on the cloth or by printing on another transfer medium and subsequently transferring the printed image on the transfer medium to the cloth.
Here, when direct printing is performed, it may be possible to perform stiffening process to provide clark stiffness to be greater than or equal to 10 and smaller than or equal to 400. Also, the cloth may contain polarized dye fixing agent so that the image can be fixed on the cloth simultaneously with printing operation. Furthermore, it is also possible to perform fixing process with the polarized dye fixing agent after completion of printing on the cloth.
In addition to this, the cloth, for which printing is completed, may be subject of heating process or wet heating process to fix the image on the cloth, and further subject of washing after fixing process.
In the ink-jet printing system according to the present invention, printing can be performed directly on various clothes generally available in the market. However, in such case, in the conventionally existing ink-jet printing apparatus, loading system is typically constructed to once release a member for depressing the cloth as the printing medium from a cylindrical platen roller to manually set the printing medium and then to depress the depression member to tightly fit the cloth on the platen roller. In such printing apparatus, most of cloth may be transported and printed. However, since the cloth is manually loaded, it is difficult to wind the cloth on the platen without causing cockling, to align the texture to the transporting direction. Therefore, difficulty is encountered in performing fine and precise printing. By repeated use of the release mechanism, the depression force may be lowered to make it difficult to stabilize transportation Also, loading operation per se a cause of low operability. Therefore, it is preferred to employ an automatic loading mechanism for the transporting means which has been frequently employed in the recent ink-jet printing apparatus. In order to enable loading of the cloth, difficulty is encountered for lack of stiffness in the cloth in comparison with the paper.
As a construction for loading the cloth to the automatic loading mechanism, there are proposals in commonly owned Japanese Patent Application No. 108226/1993 and Japanese Patent Application No. 230369/1993. In these prior proposals, stiffening and flattening of the cloth is proposed. Even in the ink-jet printing system of the present invention, it is effective to employ the stiffened cloth for fine and precise printing and stable transportation. Accordingly, in the present invention, it is preferred that the cloth is provided stiffness having clark stiffness greater than or equal to 10 and smaller than or equal to 400. It should be appreciated that clark stiffness is the value expressed by Clark method defined in JIS-P8143.
In addition, in the stiffening process, concerning the process employing sizing agent of carboxymethyl cellulose, polyvinyl alcohol, acrylamide, starch, gum tragacanth, gua gum and so forth, the sizing agent is washed through the washing process to recover the feeling of the cloth after completion of printing. In order to avoiding washing out of dye during washing, process with cationic dye or dying control process with fixing agent and so forth is typically performed before printing. However, only by such method, it may be insufficient for certain ink, further to say certain dye and ink ejection method. It is effective to add a process with dye fixing agent.
The process with dye fixing agent, herewith referred to, is preferably a process to add a polarized material to the cloth since the dye containing in the ink to be used for printing on the cloth, as coloring agent is typically ionized property. By the process for the cloth, the dye can be coagulate by ion binding during and after printing to improve fixing ability of the dye to the fiber.
Therefore, the treatment for the cloth may be performed either before or after printing. As a polarized material for such treatment, water soluble cationic high polymer, such as polyarylamine salt, polyarylsulfone, dithylarylarmmoniumchloride and so forth, anionic high polymer, such as vinyl acetate polymer, denaturation synthetic rubber and so forth.
Such polarized dye fixing agent is solved, dispersed or forming emulsion in a solvent, such as water, alcohol or so forth, and applied on the cloth by dipping, coating or spraying to impregnate or deposit. When treatment is performed after printing, it is more effective to perform treatment with the treatment liquid with increased viscosity with the non-water based type agent in order to prevent bleeding or flowing out of the dye before coagulation.
Since these treatment agent may be removed by washing, it may not degrade the feeling of the original cloth. Furthermore, for enhancing durability of image after treatment, it is also effective to perform color fixing, heat treatment, such as iron, or vapor treatment, such as steamer. Of course, the cloth may be heated during printing by the ink-jet printing system.
In addition the above, known preparatory treatment for the cloth may be applicable for the present invention as required. As examples for such known preparatory treatment, alkali material, water-soluble high polymer, synthetic high polymer, water-soluble metal salt, urea and thiourea may be contained in the cloth. The followings are the typical examples of these materials.
As alkali material, alkali metal hydroxide, such as sodium hydroxide, potassium hydroxide, amine, such as mono-, di- and triethanolamine and so forth, carbonates or alkali metal bicarbonate and so forth, such as sodium carbonate, potassium carbonate, sodium bicarbonate and so forth can be listed. Also, alkali material may include organic acid metal salt, such as calcium acetate, barium acetate and so forth, ammonia, ammonia compound and so forth. Also, sodium trichloroacetate which becomes alkali material through steaming or dry heating, may also be included in the alkali material. Particularly preferred alkali material are sodium carbonate and sodium bicarbonate.
As the water-soluble high polymer, natural water-soluble high polymer, such as corn, starches of wheat, cellulose type material, such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and so forth, polysaccharide, such as sodium aiginate, arabic rubber, locust bean gum, tragacanth gum, gua gum, tamarined seed and so forth, protein material, such as gelatin, casein and so forth, tannin type material, lignin type material may be included.
As the synthetic high polymer, polyvinyl alcohol type compound, polyethylene oxide type compound, acrylic acid type water-soluble high polymer, maleic anhydride type water-soluble high polymer and so forth are included. Among these, polysaccharide type high polymer, cellulose type high polymer are preferred.
As the water-soluble metal salt, compounds forming typical iron crystal, and having pH in a range of 4 to 10, Such as alkali metal, halide of alkali earth metal, may be included. As typical example of such compound, sodium chloride, sodium sulfate, potassium chloride, sodium acetate and so forth are included as alkali metal type compound, and calcium chloride, magnesium chloride and so forth may be included as alkali earth metal type compound. Amongst, salts of sodium, potassium, calcium are preferred.
In the preparatory treatment, there is no limitation for the method to include the material set forth above in the cloth. Typical methods may be dipping method, padding method, coating method, spraying method and so forth.
Also, in order to perform fixing process of the coloring agent in the ink, such as dye to the fiber after completion of ink-jet printing, it may be the printed product in the conventionally known method. For instance, when alkali treatment is performed as the preparatory treatment, it may be performed by steaming method, HT steaming method, thermo-fixing method and so forth. When cloth not preliminarily alkali processed is employed, the treatment may be performed by alkali pad steaming method, alkali blotch steaming method, alkali shock method, alkali cold fixing method and so forth may be employed.
It is also possible to produce the printed product by one printing the image on a transfer media and then transfer the printed image to the cloth. This is the method to print the desired mirror image to other transfer medium, then to contact the printed surface to the cloth to physical or chemical transfer and penetrate the mirror image formed on the transfer medium to the cloth. In such case, as a special printing method for cloth printing, formation of special mirror image becomes necessary in addition to adjustment of the ink ejection amount. As the transfer medium to be used for this purpose, property for appropriately holding the ejected ink and easily transfer the formed image to the cloth is required. For example, such transferring medium may be formed by forming an ink holding layer of polyvinyl alcohol, cellulose, wax and so forth on a sheet form support of polyethylene telephthalate, paper so forth. Also, as a means for transferring the image formed on the transfer medium to the cloth, known pressure transfer or melting transfer, in which the transfer medium and the cloth are stacked in tightly fitted position and pressure, heat or laser beam or solvent is applied for transferring the image. Also, the combination of the foregoing method may also be employed.
Accordingly, it is possible to add a printing mode for such transfer printing. Particularly, the foregoing transfer printing method may not be limited the printing medium to receive the transferred image to the cloth. Therefore, the image may be transferred to various printing media. Therefore, for widening the applicable printing medium, it is advantageous to provide such printing mode adapted to the transfer printing as independent mode.
Finally, for the ink-jet printed product produced through the process set forth above, it is possible to obtain final product by cutting and/or sewing the cloth. The ink-jet printing products produced by the ink-jet printing system discussed above can be treated equally to the conventional textile printing product. therefore, cutting and/or sewing can be done freely.
In any case, the ink-jet printing system according to the present invention has one or more cloth printing mode for forming image on the cloth and switching means for selecting the one or more cloth printing mode with conditions, at least one of which is differentiated from the printing condition in the mode for performing printing on the printing medium other than cloth. Therefore, the ink-jet printing apparatus according to the present invention can perform ink-jet printing not only for the conventionally existing printing medium, such as paper, OHP sheet and so forth but also for cloth, freely. The ink-jet printing system utilizing such ink-jet printing technology makes it possible to perform fine and precise color expression not only for industrial application but also for the field of hobby in home use.